2. The effect of feeding excess methionine on live performance, carcass traits, and ascitic mortality

Appetite suppressant activity of dietary excess Met was investigated in a 7-wk trial for the potential to restrict feed intake and the early growth of broilers as a means of reducing the incidence of ascitic mortality. A basal starter diet meeting the minimum NRC (1994) requirements for broilers was compared with a diet providing Met above the requirement (1.86% of the diet). Excess dietary Met was fed to the broilers from 4 to 11 d. Grower and finisher diets were provided from 22 to 35 d and from 36 to 49 d. Birds in two rooms were exposed to cool temperatures to induce ascites. The temperature program for the cool rooms was as follows: 12 h at 24 C daily (0800 to 2000) and 12 h at 15 C nightly (2000 to 0800) from 14 to 49 d, whereas the other two rooms were maintained at 24 C (control rooms). Body weight gain was depressed by 20.4% when excess Met was fed from 4 to 11 d. Feed conversion was also negatively affected by the excess dietary Met. A brief recovery was achieved from 11 to 14 d upon refeeding the well-balanced basal starter diet. Full compensatory growth was achieved by 49 d when body weight was equal to that of birds fed the basal diet. Excess dietary Met did not affect the carcass traits with the exception of abdominal fat pad, which was reduced by the excess dietary Met in the control rooms, whereas the opposite was true in the cool rooms. Ascitic mortality was not altered by dietary Met, however, the total mortality was significantly reduced by excess Met in the control rooms.